To the best of my knowledge, there is no directly related prior art because the present sheet positioning device is principally used to locate printed copy under a scanning densitometer (not heretofore known by me) as described in my copending patent application, "Color Monitoring System For Use In Creating Colored Displays", Ser. No. 951,444 which was filed on Oct. 13, 1978. As will be described more in detail hereinafter, when material is printed in color, it is the custom for the printer to print a color swatch bar, that is, a line of different blocks of the colored ink being transferred to the paper, to make up the display or picture being printed. My scanning densitometer has a scanning head which is used to pass over the swatch bar, determine what colors are present in selected swatches or block and determine the optical densities of the colors in those selected swatches. As stated earilier, since a scanning densitometer has not heretofore been used, the need for a sheet positioning means to be used therewith may not have existed. However, there are devices which may be considered as prior art, although not invalidating prior art. For instance, milling machines very often have tables which permit guides or holders to be secured thereto and the same is true for power saw devices used to cut wood or metal. In each of the foregoing arrangements, the guides are secured to the tables or beds by passing bolts or rods through threaded or unthreaded holes in the beds. The present device, while taught as being used for aligning a sheet of paper to be read by a scanning head, could be used to align a piece of metal to be ground or a piece of wood to be cut by a power saw.